A hydraulically operating support element of the pre-cited type is disclosed in EP 1 411 214 A2 which is considered to be generic. A major drawback of this support element is its relatively large design height due, among other things, to the vertically stacked arrangement of lost motion spring, coupling mechanism and hydraulic unit. It is further noted that in case of a required dismounting (for example for adjusting coupling lash), the pistons arranged as coupling elements in the inner element can only be removed with some difficulty.
In other prior art solutions, a slide forming the coupling element is arranged laterally in the cylinder head and is displaceable for effecting coupling into a corresponding engagement surface of the support element. The person skilled in the art will readily perceive that this requires complex modifications to the design of the cylinder head and that such a device needs an unnecessarily large lateral design space.